Intel Sandy Bridge Microarchitecture Preview. Page 5

In a few weeks we will start posting reviews of Intel processors based on the new Sandy Bridge microarchitecture. But while we are still bound by the NDA, we decided to sum up all the information we know about these promising new products, which doesn’t fall under the NDA.

Graphics Core Acquiring New Functions

Graphics core inside a CPU is no news. Clarkdale processors with a built-in Intel HD Graphics GPU have been in the market for almost a year now. But it is only in Sandy Bridge that graphics and computational cores have finally made friends: they are inside the same semiconductor die and are connected with the same ring bus that is also shared with other processor resources. This architectural change when the graphics core got very close to the memory controller and was granted access to the L3 cache had a positive effect on performance. However, the graphics core, just like the computational processors cores, has also been improved in many other ways, so that it has formally become a next generation component.

Overall, graphics core architecture hasn’t changed dramatically: it is still based on the same 12 execution (shader) processors. However, the developers managed to make them almost twice as fast in a number of tasks and reached higher levels of parallelism in them. Among the innovative changes we should definitely mention Shader Model 4.1 and DirectX 10.1 support.

Since graphics core has now moved into a 32 nm semiconductor die, it is now possible to easily increase its clock speed, which may go as high as 1.35 GHz. As a result, the performance of Sandy Bridge graphics core in real applications will be comparable with that of entry-level discrete graphics accelerators. Intel even thought of implementing FSAA in their integrated graphics solution! In other words, Sandy Bridge has every chance to become the fastest integrated graphics solution out there, which will even be capable of threatening the discrete graphics cards in the low-end price segment. I am pretty sure that AMD and Nvidia will object by stressing the lack of DirectX 11 support, which may come in handy not only in the latest games, but also in applications utilizing DirectCompute such as the upcoming Internet browsers.

However, improving the existing graphics core architecture was not the only thing they’ve done in this department. They also equipped the graphics core of the new Sandy Bridge processors with special new units intended for video decoding and encoding in popular formats, such as MPEG2, VC1 and AVC.

Of course, hardware video decoding is not something revolutionary these days, even the Clarkdale graphics core can do it just fine. However, this operation used to be the responsibility of shader processors, while now there is a special functional unit in charge of it. This rearrangement of responsibilities was required for proper support of 3D video: the new graphics core can easily cope with hardware decoding of stereo 3D Blu-ray or MVC streams.

Another interesting addition is the hardware codec that can encode video into AVC format. In practical terms it means that Sandy Bridge has all the resources necessary for fast video transcoding without utilizing any of the traditional CPU resources for that purpose. And keeping in mind how popular Intel processors are these days, it will most likely be actively employed by software developers. Especially, since hardware encoding and decoding units can also be used in Intel P67 based systems, i.e. in systems with an external graphics card.

And the examples are right here: we all know that media functionality of the new Sandy Bridge processors will be supported in such popular applications as ArcSoft MediaConverter, Corel DVD Factory, CyberLink MediaEspresso, Movavi Video Converter, Roxio Creator, etc. And by the way, when multimedia units inside Sandy Bridge graphics core are utilized for video transcoding, shader processors remain free, so they can give a hand in additional video processing or applying special effects.

Different processors on Sandy Bridge microarchitecture will have one of the following graphics core modifications: Intel HD Graphics 2000 and Intel HD Graphics 3000. They differ by the number of active execution (shader) processors. The top GPU model positioned for mobile solutions and top desktop CPUs will have all 12 execution units, while the “lite” version of the same core, Intel HD Graphics 2000, will only have six units like that. Intel HD Graphics 2000 will also work at a slightly lower frequency. However, the most interesting GPU components, namely – hardware encoder and decoder – will be untouched and identical in both GPU modifications.